The chemical and physiological properties of a crosslinked dimer of pancreatic ribonuclease are being studied. The optimum conditions for its preparation with dimethyl suberimidate are being established and the product is being assayed both chemically and physiologically in tests in which its greater activity than that of the monomer toward double-stranded RNA's could be advantageous. Another ribonuclease under study is a form of the pancreatic enzyme that has almost equal activity at pH 4.5 and pH 7.5; its sensitivity to acid and heat has caused it to be overlooked during the usual procedure for the preparation of RNase A. Researches on deoxyribonucleases include study of the reversible denaturation of DNase A by sodium dodecyl sulfate, the synthesis of a new synthetic substrate for the enzyme, and examination of the possibility that gamma-carboxyglutamic acid could be present as a constituent amino acid contributing to the special Ca2 ion binding capacity of the enzyme. Proteases have been used to study the positioning of rhodopsin in the disc membrane of the photoreceptor rod cell of the bovine retina.